Labyrinth air caster and method of manufacture thereof



y 7, 1966 H- A. MACKIE 3,251,431

LABYRINTH AIR CASTER AND METHOD OF MANUFACTURE THEREOF Filed May 21, 1962 INVENTOR.

ATTORNEY United States Patent 3,251,431 LABYRINTH AIR CASTER AND METHOD OF MANUFACTURE THEREOF Harry A. Mackie, Birmingham, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation ofDelaware Filed May 21, 1962, Ser. No. 196,362

4 Claims. (Cl. 180-7) This invention relates to low pressure air bearings and more particularly to a unitary labyrinth form of air bearing especially suited for attachment to household appliances and other bulky objects to facilitate movement thereof with minimum manual effort.

The invention is particularly concerned with the manufacture and utilization of an air bearing device especially suited for mass production in continuous strip form, selected lengths being cut from the continuous strip for permanent or temporary attachment to the bottom surface of various bulky appliances, boxes, crates and the like.

An object of the invention is to provide a labyrinth air caster which is sufliciently economical to fabricate as to enable application thereof to standard household appliances, as a permanent part of the appliance.

A further object is to provide an improved air bearing comprising a multiplicity of discretely arranged annular inflatable portions each forming with the supporting surface thereunder a generally frusto-conical plenum chamber.

Another object is to provide an air caster of the type described in which the defined configuration is established by preforming a sheet of flexible material as by heat and pressure, and thereafter bonding the preformed material to a flat sheet of flexible material.

These and other objects, advantages and features of the invention will become more fully apparent as reference is had to the accompanying specification and drawing wherein:

FIGURE 1 is a perspective view of a typical home appliance having a labyrinth air bearing, in accordance with the invention, secured to the underside thereof;

FIGURE 2 is a fragmentary front elevational view of the structure shown in FIGURE 1;

FIGURE 3 is a fragmentary bottom plan view of the labyrinth a'u bearing; and

FIGURE 4 is a view looking in the direction of arrows 4-4 of FIGURE 3.

Referring now to the drawing and particularly FIG- URE 1, there is shown a conventional kitchen range 2 of a type commonly found in modern households. Range 2 includes laterally spaced parallel runner portions 4 and 6 which-normally rest upon the floor 8 when the range is in installed position. Due to the relatively great weight of kitchen ranges and other household appliances, in the past, movement thereof from installed positions occurred infrequently. As a result, the area directly beneath the appliance as well as the rear of the appliance and the adjacent wall presented a diflicult problem in terms of housekeeping. In accordance with the present invention, extreme ease of mobility is achieved by the provision of a labyrinth type air caster 10 which is readily attached to the lower surface 12 of the appliance as a permanent part thereof, to facilitate ease of movement of the appliance by a physical effort of a very low order. Air caster 10 is adapted, in a manner shortly to be described, for connection to a suitable source of low pressure air, not shown, such as a household vacuum cleaner. Upon energization in the manner mentioned, air caster 10 develops a discretely organized pattern of load supporting superatmospheric pressure areas between the lower surface of the appliance and the floor which both elevate the appliance sufliciently to eliminate frictional engagement between the runners 4 pressed troughs 20.

and 6 and the floor 8 and support both the caster 10 and appliance in frictionless spaced relation with the floor so that the appliance may be moved horizontally over the floor by only such physical effort as is required to overcome inertia.

As seen best in FIGURES 3 and 4, the labyrinth air caster 10 is formed by an upper flat sheet of plastic film 14 and a lower convoluted sheet 16 of similar material. Lower sheet 16 is preferably preformed as by dielectric embossment to form a discrete pattern of annular depressions 18 and longitudinally extending interconnecting de- At predetermined intervals longitudinally of sheet 16, the otherwise discrete'mentioned pattern is interrupted by a main transversely extending trough 22 which connects with troughs 20 and extends to the edge 24 of sheet 16. Near the edge 24,trough 22 gradually expands for connection with a flexible air inlet tube 26 which in turn is adapted for coupling to a standard size vacuum cleaner hose, not shown.

In accordance with the invention, the upper sheet 14 and lower sheet 16 of air caster 10 are dielectrically or otherwise bonded together throughout the entire adjacent areas surrounding annular portions18, troughs 20 and 22 and at the spot centers 28 located within annular portions 18. As seen in FIGURE 4, when the respective sheets 14 and 16 are bonded in the manner described, there are provided a plurality of annular cavities 30 which are in common communication with air inlet 26 via troughs 20 and 22. Each annular cavity 30 is vented into the frustoconical cavity 32 bounded by portion 18 by pairs of apertures 34 and 36 formed in portions 18 between spot centers 28 and the lowermost extremity 38 of each annular portion. Accordingly, when low pressure air is introduced through inlet tube 26, each of the annular cavities 30 are inflated to yieldably maintain the preformed con-. figuration and continuing flow of air through apertures 34 and 36 into the plurality of generally frusto-com'cal plenum cavities 32 formed below spot centers 28 and bounded by an imaginary circle defined by the lowermost extremity 38 of depressed portions 18. The low pressure air emerging into cavities 32 exerts a lifting force calculated according to the area circumscribed multiplied by the plenum cavity air pressure to lift and maintain the appliance or other load thereon in frictionless relation to a floor surface.

The efiiciency of the described device is enhanced by two factors. First, the yielding pressure exerted by air within the annular cavities 30 tends to maintain :a highly uniform and shallow throttling gap 40 between the lowermost extremity 38 of each annular portion 18 which assures minimum peripheral air loss. Second, each of the individual annular bearing members acts as cumulative barriers to leakage from the additional bearings located inboard thereof.

Of paramount importance in the present invention is the fact that the entire caster 10 is particularly suited for manufacture on a continuous run basis. That is, the upper plastic layer 14 and lower plastic layer 16 may be bonded together in indefinite lengths and subsequently cut to suitable lengths for a given application. In addition, because caster 10 is unitary in form and entirely selfcontained for operational purposes, application thereof to -any fiat surface requires only sufiicient securement to establish placement. Thus, for example, the edges of the plastic material may be tacked at intervals to the bottom surface of a crate, or cemented, taped or otherwise secured to the flat metal bottom of an appliance or similar article.

While but one embodiment of the invention has been shown and described, it will be apparent that other changes and modifications may be made therein. It is, therefore, to be understood that it is not intended to limit the invention to the embodiment shown, but only by the scope of the claims which follow.

I claim:

1. A low pressure .air energized caster comprising, a two layer laminate of flexible non-porous material bonded together, the upper layer being substantially fiat and the lower layer being preformed with a plurality of discretely arranged downwardly bulged communicating annular cavities, means formed in the lower layer venting each of said cavities to atmosphere radially inboard of the lowermost bulged extremity of each annular cavity, and conduit means attached to said laminate for connecting said cavities in communicating relation with a source of low pressure air.

2. A labyrinth air caster comprising, a substantially flat upper sheet of flexible material, a lower sheet of flexible material having a plurality of annular depressed portions formed therein at uniformly spaced intervals, longitudinally extending trough-like depressions formed in said lower sheet interconnecting said annular depressions, a transverse trough-like portion formed in said lower sheet at predetermined longitudinal intervals connecting said longitudinal trough-like portions, said lastmentioned trough-like portion extending to the edge of said lower sheet on one side only, said upper and lower sheets being hermetically bonded together throughout the entire area bounding said annular depressions and troughlike portions, and a plurality of openings formed in said annular depressed portions radially inwardly of the area circumscribed by the lowermost extremity of said depressed portions.

3. A labyrinth air caster comprising, a substantially flat upper sheet of flexible material, a lower sheet of flexible material having a plurality of annular depressed portions formed therein at uniformly spaced intervals both longitudinally and transversely, longitudinally and transversely extending trough-like depressions formed in said lower sheet interconnecting said annular depressions, a transverse trough-like portion formed in said lower sheet at predetermined longitudinal intervals connecting said longitudinal trough-like portions, said last-mentioned trough-like portion extending continuously substantially the entire width of said lower sheet and opening on one side only, said upper and lower sheets being hermetically bonded together throughout the entire area bounding said annular depressions and trough-like portions, and a plurality of openings formed in said annular depressed portions radially inwardly of the area circumscribed by the lowermost extremity of said depressed portions.

4. In combination with a box-like load having a generally flat lower surface, a sheet-like plastic bearing member attached to and underlying substantially all of said lower surface, said bearing member comprising an upper flat layer and a lower layer having a uniform pattern of depressions, said layers being hermetically bonded together throughout the entire area surrounding said uniform depression pattern so that the latter forms with the ver-' tically adjacent surface of said flat layer a plurality of annular cavities each surrounding a plenum cavity and a plurality of trough-like portions interconnecting said annular cavities, aperture means in said lower layer connecting each of said annular cavities in communication with the plenum cavity surrounded thereby, and conduit means connected to said bearing member for introducing air under pressure into said communicating annular cavities through said trough-like portions.

References Cited by the Examiner UNITED STATES PATENTS 3,055,446 9/1962 Vaughen 180-7 3,082,836 3/1963 Billman 180-7 3,161,247 12/1964 Mackie 180-7 A. HARRY LEVY, Primary Examiner. 

1. A LOW PRESSURE AIR ENERGIZED CASTER COMPRISING, A TWO LAYER LAMINATE OF FLEXIBLE NON-POROUS MATERIAL BONDED TOGETHER, THE UPPER LAYER BEING SUBSTANTIALLY FLAT AND THE LOWER LAYER BEING PERFORMED WITH A PLURALITY OF DISCRETELY ARRANGED DOWNWARDLY BULGED COMMUNICATING ANNULAR CAVITIES, MEANS FORMED IN THE LOWER LAYER VENTING EACH OF SAID CAVITIES TO ATMOSPHERE RADIALLY INBOARD OF THE LOWERMOST BULGED EXTREMITY OF EACH ANNULAR CAVITY, AND CONDUIT MEANS ATTACHED TO SAID LAMINATE FOR CONNECTING SAID CAVITIES IN COMMUNICATING RELATION WITH A SOURCE OF LOW PRESSURE AIR. 